Dialyzing fluids for perfusing artificial kidney systems (hereinafter referred to merely as "dialyzing fluid" unless otherwise indicated) currently available are roughly classified into acetate-containing dialyzing fluids and bicarbonate-containing dialyzing fluids.
The acetate-containing dialyzing fluids and bicarbonate-containing dialyzing fluids ready for use usually have the following compositions.
______________________________________ (A) Acetate-containing dialyzing fluids Na.sup.+ 126-145 mEq/l K.sup.+ 1.5-3.0 mEq/l Ca.sup.++ 2.5-4.0 mEq/l Mg.sup.++ 1.0-1.5 mEq/l Cl.sup.- 98-108 mEq/l CH.sub.3 COO.sup.- 30-42.5 mEq/l Glucose 0-300 mg/dl (B) Bicarbonate-containing dialyzing fluids Na.sup.+ 135-140 mEq/l K.sup.+ 0-4.0 mEq/l Ca.sup.++ 2.5-3.5 mEq/l Mg.sup.++ 1.0-1.5 mEq/l Cl.sup.- 106-107.5 mEq/l CH.sub.3 COO.sup.- 4-9 mEq/l HCO.sub.3.sup.- 27.5-35 mEq/l ______________________________________
Commercially available acetate-containing dialyzing fluids comprise in combination a concentrated dialyzing fluid and glucose either contained therein or provided separately as a second fluid and are diluted with water before use to give the composition of dialyzing fluid (A).
Commercially available bicarbonate-containing dialyzing fluids comprise in combination a concentrated dialyzing fluid and sodium bicarbonate provided separately as a second fluid and are diluted with water before use to give the composition of dialyzing fluid (B).
These commercially available concentrated dialyzing fluids are usually contained in a container of polyethylene or the like having a volume of about 10-l volume, consequently entailing numerous problems on storing space, difficulty in transport and like handling. Further the above concentrated dialyzing fluids readily undergo changes in pH or in composition during storage and thus are difficult to adjust to the desired pH before use and to provide with the intended composition, hence problematic also in quality stability.
To overcome these problems, we conducted extensive research and developed a process for producing a dialyzing powder by spray drying method using an aqueous solution of electrolyte compounds similar in composition to the dialyzing fluid (A) or (B) (without glucose) (Japanese Examined Patent Publication No. 34248/1982). We also developed a process for producing a bicarbonate-containing dialyzing powder, the process comprising pulverizing sodium chloride as the chief component among electrolyte compounds to particles of about 20 to about 30 .mu.m, spraying glacial acetic acid over the particles for adsorption, and mixing the particles with other electrolytic compounds (Japanese Examined Patent Publication No. 27246/1983). The dialyzing powders of mixed electrolytic compounds obtained by these processes obviate the storing-space and handling problems, but raise other problems on producing process, quality, storage, etc. as described below.
The dialyzing powders obtained by the spray-drying method are irregular in water content and particle size. Particularly the bicarbonate-containing dialyzing powders are difficult to adjust to the desired pH.
The method spraying the glacial acetic acid over the sodium chloride powder for adsorption results in emission of offensive odor and thus in deterioration of work environment, and entails difficulty in eliminating the irregularity in amounts of minor components in the production lot.
The dialyzing powders are prone to change in pH. And NaCl, KCl, MgCl.sub.2, CaCl.sub.2 and the like for use as the active components have the property of solidifying on absorption of moisture, tending to solidify during storage. After solidification, the dialyzing product becomes difficult to dissolve before use.
Moreover, loss of powder is likely to occur due to scattering during the formation of an aqueous solution of powder.